Motion sensing lock for securing a cover or guard for a rotatable member such as a centrifugal contactor shaft

ABSTRACT

A cover or guard for a machine having a rotatable member such as a shaft is secured by a lock having a motion sensing probe which prevents opening of the cover if the rotatable member is in motion. The motion sensing probe extends to a position of proximity with the rotatable member or shaft and may be moved from an &#39;&#39;&#39;&#39;at rest&#39;&#39;&#39;&#39; position in which the probe is spaced from the rotating part in a direction to engage the rotating part, and wherein probe controlled mechanism, maintaining the lock in locked position when the probe is &#39;&#39;&#39;&#39;at rest&#39;&#39;&#39;&#39;, is operable to disable the lock only if the rotatable member is not rotating when engaged by the motion sensing probe.

United States Patent Balazer, deceased et a1.

MOTION SENSING LOCK FOR SECURING A COVER OR GUARD FOR A ROTATABLE MEMBERSUCH AS A CENTRIFUGAL CONTACTOR SHAFT Inventors: Richard J. Balazer,deceased, late of Saginaw, Mich.; James A. Farrand, administrator,Saginaw, Mich.

Assignee: Baker Perkins, Inc;, Saginaw, Mich.

Filed: Nov. 24, 1972 Appl. No.: 308,967

[ Feb. 18, 1975 2,955,693 10/1960 Renault et al. 192/136 FOREIGN PATENTSOR APPLICATIONS 442,309 2/1936 Great Britain 210/146 PrimaryExaminerGeorge H. Krizmanich Attorney, Agent, or FirmLearman & McCulloch[57] ABSTRACT A cover or guard for a machine having a rotatable membersuch as a shaft is secured by a lock having a motion sensing probe whichprevents opening of the cover if the rotatable member is in motion Themotion sensing probe extends to a position of proximity with therotatable member or shaft and may be moved from an at rest position inwhich the probe is spaced from the rotating part in a direction toengage the rotating part, and wherein vprobe controlled mechanism,maintaining the lock in locked position when the probe is at rest, isoperableto disable the lock only if the rotatable member is not rotatingwhen engaged by the motion sensing probe.

14 Claims, 6 Drawing Figures PATENTEDFEB18I9Y5 7 SHEET 10F 2 MOTIONSENSING LOCK FOR SECURING A COVER OR GUARD FOR A ROTATABLE MEMBER SUCHAS A CENTRIFUGAL CONTACTOR SHAFT BACKGROUND OF THE INVENTION Governmentregulations relating to the design of machinery are today concerned withthe safety of the machine operator and seek to prevent him from beinginjured even when he is negligent in the handling and operation of themachinery. Thus, there is a considerable need for a simple andinexpensive cover lock for rotating equipment such as centrifuges.

One of the prime objects of the present invention is to design amotion-sensing lock which normally maintains a cover for a rotatablepart in locked position and permits it to be opened only at a time whenthe shaft or other rotatable part is stationary.

A further object of the invention is to design a simple and compactmechanical motion sensitive and responsive lock of the type described,which can be unlocked only if the operator physically moves the lockinto engagement with the rotatable part at a time when the rotatablepart is stationary.

Still another object of the invention is to provide a mechanicallyoperated, fail-safe lock incorporating a shaft engaging probe which ismoved to collapsed position if the shaft is rotating when the probeengages it.

Another object of the invention is to provide a device of the characterdescribed which will find wide use in industry on myriad devices of alltypes including, for example, machine tools, power-driven yard and shopequipment, and even various household appliances.

Another object of the invention is to provide a lock of the typedescribed which avoids the use of electrical circuitry and theexplosion-proof enclosures rendered necessary to house the circuitry onsome equipment.

A final object of the invention is to provide a highly reliable sensingdevice which can be very economically manufactured and assembled.

Other objects and advantages of the invention will be pointed outspecifically or will become apparent from the following description whenit is considered in conjunction with the appended claims and theaccompanying drawings, in which:

FIG. 1 is a partly sectional, somewhat schematic view showing a machinehaving a cover for a rotatable part which is latched by a lockconstructed according to the present invention;

FIG. 2 is an enlarged, fragmentary elevational view, taken on line 2-2of FIG. 1;

FIG. 3 is a considerably enlarged, fragmentary side elevational view ofthe lock or latch mechanism illustrating the parts with greater clarity;

FIG. 4 is a partly sectional, side elevational view with the lock deviceshown in the at rest position;

FIG. 5 is a similar view with the lock mechanism shown as moved toengage the probe with a shaft at the time the shaft is stationary; and

FIG. 6 is a similar view showing the position of the lock parts at atime when the lock probe is moved to engage a rotating shaft and ispivoted thereby to a partly displaced position.

Referring now more particularly to the accompanying drawings in whichonly a preferred embodiment of the invention has been shown, and in thefirst instance more particularly to FIG. 1, a numeral 10 generallyindicates the frame of a machine which has suitable bearings formounting a rotatable member such as a rotor 11 which is schematicallydepicted. The base 10 in-- cludes a front wall 12 and a rear support bar13, and a semi-cylindrical cover 14 is hinged to the bar 13 in anysuitable manner, as with pins 15, and is swingable upwardly in thedirection indicated by arrow a to a near vertical position such that theshaft or rotatable part or member 11 is exposed.

Mounted on the front of the cover 14 is a latch member 16, having abifurcated vertical plate 17, formed with terminal claw members 18. Theclaw members 18 embrace a lock mechanism generally designated Lsupported on the wall 12 for movement in toward, and out away from, therotatable member or shaft 11 in a manner which presently will bedescribed. The lock mechanism L includes an outer casing 19 having abore 20 for an internal slide or plunger 21 which is adapted to extendthrough a rectangular opening 22 provided in the wall 12 which preventsrotation of the slide 21.

At the inner end of the slide or plunger 21, a pin 23 pivotally mounts aprobe 24, which, as FIGS. 5 and 6 indicate, can be moved into engagementwith the rotatable part or shaft 11. As will later develop, when thepart 11 is rotating in the direction 11, the probe 24 is pivoted to theposition in which it is shown in FIG. 6 by the rotating shaft. A spring25 is provided in the bore 20, and a spring 26 is likewise provided in acounterbore 27 at the inner end of casing 19, for purposes which willlater become more apparent.

Also provided in the casing 19 to communicate with the bore 20, is abayonet slot 28 having a lateral leg portion 28a and an axiallyextending leg portion 28b. A pin 29, fixed to the plunger 21, isreceived in the bayonet slot 28 and when the locked device is in therest position, will be disposed in the axially extending leg portion 28bas shown in FIG. 4.

Also provided on the casing 19 are a pair of diametrically oppositeflats or grooves 30 (see FIG. 3) which, when the casing is in the rotarypostion shown in FIGS. 24, for instance, are angularly removed from theopening 31 between claws l8. Handlebars 32, provided on the casing 19,facilitate 90 rotation of the casing 19, which is possible only when thepin 29 is disposed in the lateralslot portion 28a as illustrated in FIG.5, to line up the flats 30 with the claw mouth 31. When the casing 19 isrotated to this position, the latch 17 can be raised upwardly past thecasing 19 in raised upwardly past the casing 19 in the direction a, toswing the cover upwardly about pivot pin 15.

THE OPERATION FIGS. 3 and 4 show the lock mechanism in an at rest" ornormal position in which the probe 24 is disposed a distance c from therotor 11. In this position of the locked parts, the spring 26 forces thecasing 19 outwardly to the position indicated, and the spring 25 isexerting pressure on the slide 21. The flats 30 are disposed axiallyoutwardly of the opening 31, and the casing 19, with the pins 29 in theaxial portion 28b of slot 28, is angularly displaced 90 from a positionin which the mechanism could be unlocked. In the position of the partsshown in FIG. 4, whether the rotor 11 is rotating or not, the latchplate 17 clearly cannot be lifted upwardly past the claws 18 (see FIG.2).

If the operator now wishes to lift the cover 14, and presses inwardly oncasing 19 to cause the probe 24 to engage a non-rotating rotor 11, andthe spring 26 to be compressed, the pin 29 is forced upwardly in theaxial of slot 28 to the position shown in FIG. 5. This occurs, if therotor 11 is stationary and the probe 24 remains in axial alignment withthe slide 21. In this position of the parts,'the spring 25 is, in fact,exerting a pressure on slide 21 urging it into engagement with the rotor11. With the pin 29 in the position shown in FIG. 5, clearly, thehandlebars 32 can be grasped and the casing 19 can be rotated 90 tobring the flats 30 to the position illustrated in FIG. in alignment withthe opening 31 between claws 18. ln this position of the parts, theflats 30 line up with the opening 31 and the latch 17 can be liftedupwardly in the direction a to swing cover 14 upwardly.

If, however, the rotor 11 is rotating, as for instance in the directionb, the probe 24 is pivoted to the cocked or axially collapsed positionin which it is shown in FIG. 6 and the pin 29 remains in the axialportion 28b of the bayonet slot 28 and prevents any unlocking rotationof the casing 19. If the operator then releases the casing 19, thespring 26 will return it to the position in which it is shown in FIGS. 3and 4. A torsion spring 33 can be connected between the pin 23 and probe24 to positively assure movement of the probe 24 back to the position inwhich it is shown in FIGS. 3 and 4. If the lock mechanism is used invertical position, rather than a horizontally disposed position asillustrated, the forces of gravity will, of course, take care of movingthe probe 24 back to the axially aligned position.

It is to be understood that the drawings and descriptive matter are inall cases to be interpreted as merely illustrative of the principles ofthe invention, rather than as limiting the same in any way, since it iscontemplated that various changes may be made in various elements toachieve like results without departing from the spirit of the inventionor the scope of the appended claims.

What is claimed is:

1. A machine comprising: a framework, a drivable part, such as acentrifugal rotor, movably mounted on said framework; a releasable guardfor the part; a latch part mounted on one of said framework and saidguard; a rotatable lock member having a cylindrical bore supported forrotary movements about the axis of said bore between a position in whichit coacts with said latch part to fix said guard in a position in whichit cannot be released and a position in which said guard can bereleased; and motion sensing element means slidably received in saidrotatable lock member for engaging said drivable part and controllingwhether said lock member can be rotated between said positions.

2. The combination of claim 1 wherein said rotation sensing elementmeans comprises a probe pivotally supported on said lock member toextend therefrom so that engagement with a drivable part pivots it froma normal position of extension to an axially collapsed position.

3. A machine comprising: a framework; a drivablev part, such as arotatable, centrifugal rotor, movable on said framwork in an endlesspath; a releasable guard for the part; a latch part mounted on one ofsaid framework and said guard; a lock member supported for rotarymovements about an axis between a position in which it coacts with saidlatch part to fix said guard in a position in which it cannot bereleased and a position in which said guard can be released; and motionsensing clement means on said lock member for engaging said drivablepart and controlling whether said lock member can be rotated betweensaid positions, said lock member being mounted for axial movement tomove said sensing element means into and out of engagement with saidrotatable part; and mechanism for permitting or preventing rotation ofsaid lock member depending on the axial position of said lock member;said sensing element means comprising a probe part mounted on said lockmember to engage said rotatable part and prevent further axial movementof said sensing element means toward said rotatable part when therotatable part is stationary while permitting axial movement of saidlock member relative thereto to an axially inner position in which itcan be rotated to a guard releasing position, said probe part beingdisplaceable to a position permitting further axial movement of saidsensing element means and said lock member toward said rotatable partwhen the rotatable part is rotating so that relative movement of saidsensing element means and said lock member is not effected and said lockmember cannot be rotated to said guard releasing position.

4. The combination defined in claim 3 in which said mechanism forpermitting or preventing rotation of said lock member comprises abayonet slot in said lock member and a pin controlled at least in partby the position of said probe extending into said slot and preventingrotation of said lock member when positioned in one portion of saidslot.

5. The combination defined in claim 4 in which said lock membercomprises a casing mounted for axial movement and having said bore witha slide movable axially therein; said bayonet slot comprising a lateralleg portion and an axial leg portion in said casing; and said pinextending from said slide into said slot.

6. The combination defined in claim 5 in which a spring positioned inthe bore normally maintains said pin in the axial leg portion of theslot in a position preventing rotation of the casing.

7. The combination defined in claim 6 in which said casing is mounted onthe framework of the machine which has an opening communicating withsaid bore and slidably, but non-rotatably, passing said slide; and aspring between said framework and lock casing normally holding saidcasing in a position in which the probe is removed from the rotatablemember.

8. The combination defined in claim 7 in which said probe part isnormally maintained by said latter spring at a spaced distance from therotatable part equal to the length of the axial portion of the slot.

9. A machine including: a rotatable part; a frame supporting said partfor rotation; a cover for said rotatable part; a lock for said coverhaving probe means, connected thereto for movement between a positionengaging said part and a position removed from said part, forconditioning the lock for unlocking movement when engaged with therotatable part when the part is at rest, said probe means beingdisplaceable to a displaced position preventing unlocking of the coverwhen engaged with the part when the part is rotating, and means normallyurging said lock and said probe means to positions removed from therotatable part.

10. The combination defined in claim 9 wherein mechanism preventsmovement of the lock to unlock the cover when the lock and means are insaid removed position.

11. A machine including: a rotatable part; a frame supporting said partfor rotation; a cover for said part; a lock for said cover having probemeans connected thereto, movable between a part engaging position and aremoved position for conditioning the lock for unlocking movement whenengaged with the rotatable part when the part is at rest, said probebeing movable to a displaced position preventing unlocking of the coverwhen engaged with the part when the part is rotating; said lockincluding a casing mounted for rotation and an axially movable slidetherein, to the inner end of which said probe is connected, latchmechanism is connected between said slide and easing which in oneposition permits rotation of said casing, and in another preventsrotation thereof; and spring means maintain ing said latch mechanism ina position to prevent casing rotation when said probe is moved to adisplaced position.

12. The combination defined in claim 11 in which said spring meanscomprises a spring between said casing and slide and a spring betweensaid frame and casing.

13. A machine comprising: a driveable member, such as a centrifugalcontactor shaft; a guard for said drive able member movable between aguard position adjacent said driveable member and a removed position; anenableable and disableable lock having a probe portion which is mountedfor movement to and from a position of engagement with said driveablemember; and means operated under the control of said probe portion forenabling or disabling said lock dependent on whether the driveablemember is moving or stationary when engaged by the probe portion; saidlock being mounted on the frame of the machine for movement toward andaway from the driveable member; said guard including a part embracing aportion of the lock part to normally prevent movement of the guard tosaid removed position; said lock having a portion of decreased girth ata spaced distance from said lock part portion which is normally embracedwhich enables release of said cover when the probe portion is pressedinto engagement with the rotatable member at a time when the latter isat rest.

14. The combination defined in claim 13 in which said portion ofdecreased girth comprises cutaway side portions of said lock which mustbe rotated to permit release of said guard; and said mechanism operatedunder control of said probe portion prevents or, en-

ables rotation of said lock.

1. A machine comprising: a framework, a drivable part, such as acentrifugal rotor, movably mounted on said framework; a releasable guardfor the part; a latch part mounted on one of said framework and saidguard; a rotatable lock member having a cylindrical bore supported forrotary movements about the axis of said bore between a position in whichit coacts with said latch part to fix said guard in a position in whichit cannot be released and a position in which said guard can bereleased; and motion sensing element means slidably received in saidrotatable lock member for engaging said drivable part and controllingwhether said lock member can be rotated between said positions.
 2. Thecombination of claim 1 wherein said rotation sensing element meanscomprises a probe pivotally supported on said lock member to extendtherefrom so that engagement with a drivable part pivots it from anormal position of extension to an axially collapsed position.
 3. Amachine comprising: a framework; a drivable part, such as a rotatable,centrifugal rotor, movable on said framwork in an endless path; areleasable guard for the part; a latch part mounted on one of saidframework and said guard; a lock member supported for rotary movementsabout an axis between a position in which it coacts with said latch partto fix said guard in a position in which it cannot be released and aposition in which said guard can be released; and motion sensing elementmeans on said lock member for engaging said drivable part andcontrolling whether said lock member can be rotated between saidpositions, said lock member being mounted for axial movement to movesaid sensing element means into and out of engagement with saidrotatable part; and mechanism for permitting or preventing rotation ofsaid lock member depending on the axial position of said lock membeR;said sensing element means comprising a probe part mounted on said lockmember to engage said rotatable part and prevent further axial movementof said sensing element means toward said rotatable part when therotatable part is stationary while permitting axial movement of saidlock member relative thereto to an axially inner position in which itcan be rotated to a guard releasing position, said probe part beingdisplaceable to a position permitting further axial movement of saidsensing element means and said lock member toward said rotatable partwhen the rotatable part is rotating so that relative movement of saidsensing element means and said lock member is not effected and said lockmember cannot be rotated to said guard releasing position.
 4. Thecombination defined in claim 3 in which said mechanism for permitting orpreventing rotation of said lock member comprises a bayonet slot in saidlock member and a pin controlled at least in part by the position ofsaid probe extending into said slot and preventing rotation of said lockmember when positioned in one portion of said slot.
 5. The combinationdefined in claim 4 in which said lock member comprises a casing mountedfor axial movement and having said bore with a slide movable axiallytherein; said bayonet slot comprising a lateral leg portion and an axialleg portion in said casing; and said pin extending from said slide intosaid slot.
 6. The combination defined in claim 5 in which a springpositioned in the bore normally maintains said pin in the axial legportion of the slot in a position preventing rotation of the casing. 7.The combination defined in claim 6 in which said casing is mounted onthe framework of the machine which has an opening communicating withsaid bore and slidably, but non-rotatably, passing said slide; and aspring between said framework and lock casing normally holding saidcasing in a position in which the probe is removed from the rotatablemember.
 8. The combination defined in claim 7 in which said probe partis normally maintained by said latter spring at a spaced distance fromthe rotatable part equal to the length of the axial portion of the slot.9. A machine including: a rotatable part; a frame supporting said partfor rotation; a cover for said rotatable part; a lock for said coverhaving probe means, connected thereto for movement between a positionengaging said part and a position removed from said part, forconditioning the lock for unlocking movement when engaged with therotatable part when the part is at rest, said probe means beingdisplaceable to a displaced position preventing unlocking of the coverwhen engaged with the part when the part is rotating, and means normallyurging said lock and said probe means to positions removed from therotatable part.
 10. The combination defined in claim 9 wherein mechanismprevents movement of the lock to unlock the cover when the lock andmeans are in said removed position.
 11. A machine including: a rotatablepart; a frame supporting said part for rotation; a cover for said part;a lock for said cover having probe means connected thereto, movablebetween a part engaging position and a removed position for conditioningthe lock for unlocking movement when engaged with the rotatable partwhen the part is at rest, said probe being movable to a displacedposition preventing unlocking of the cover when engaged with the partwhen the part is rotating; said lock including a casing mounted forrotation and an axially movable slide therein, to the inner end of whichsaid probe is connected; latch mechanism is connected between said slideand casing which in one position permits rotation of said casing, and inanother prevents rotation thereof; and spring means maintaining saidlatch mechanism in a position to prevent casing rotation when said probeis moved to a displaced position.
 12. The combination defined in claim11 in which said spring means comprises a spring between said casing andslide and a spRing between said frame and casing.
 13. A machinecomprising: a driveable member, such as a centrifugal contactor shaft; aguard for said driveable member movable between a guard positionadjacent said driveable member and a removed position; an enableable anddisableable lock having a probe portion which is mounted for movement toand from a position of engagement with said driveable member; and meansoperated under the control of said probe portion for enabling ordisabling said lock dependent on whether the driveable member is movingor stationary when engaged by the probe portion; said lock being mountedon the frame of the machine for movement toward and away from thedriveable member; said guard including a part embracing a portion of thelock part to normally prevent movement of the guard to said removedposition; said lock having a portion of decreased girth at a spaceddistance from said lock part portion which is normally embraced whichenables release of said cover when the probe portion is pressed intoengagement with the rotatable member at a time when the latter is atrest.
 14. The combination defined in claim 13 in which said portion ofdecreased girth comprises cutaway side portions of said lock which mustbe rotated to permit release of said guard; and said mechanism operatedunder control of said probe portion prevents or, enables rotation ofsaid lock.